Chemo is like "carpet-bombing" whereas the new cell-targeted drugs are like "smart-bombs."
chemo drugs are attracted to fast-growing cells, a chief characteristic of many cancer cells.
Unless a cell can divide and replicate itself, the cell will die. Stopping cell division can stop cancer.
All chemo drugs impair or disrupt cell division -- but they do so at different stages in the cell cycle.
Chemo drugs work at different cycles in the cells replication. For example, the chemo agent 5FU works at the "S Phase." A chemo "cocktail" could have three different agents each working at different phases of the cell cycle. There are about 60 approved chemo agents that can be effective in different combinations.
Collateral Damage... chemo also kills other fast growing cells in the body -- like those found in hair and intestines; that explains side effects like hair loss and nausea.
Fire... "cell kill" happens when chemo thwarts cell division; unable to replicate itself the cancer cells die off.